JPH0649630Y2 - Bucket controller for a swivel excavator - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a bucket control device for a swivel excavator capable of holding a bucket at a constant angle with respect to a horizontal plane even if the attitude of a working machine changes. Regarding

[Conventional technology]

Conventionally, a swing excavator such as a power shovel is equipped with a working machine having a bucket, and this working machine enables excavation work.

Further, the working machine is provided with an angle detector that detects the angle of the bucket, the angle of the arm, and the angle of the boom, and a new bucket angle is calculated based on the angles detected by these detectors. It is well known that the bucket is always kept at a constant angle with respect to the horizontal plane even if the posture is changed so as to prevent scooped earth and sand from spilling from the bucket.

[Problems to be solved by the invention] However, in a conventional control device, a control system such as PID is used to control an object to be controlled so as to follow a constantly changing target value. As shown in the figure, a steady error (b) occurs with respect to the target value (b), which makes it difficult to control with high accuracy. When the control gain is increased to reduce the error, hunting occurs as shown in the curve (c). There was a problem such as damage to the work machine and spilling of scooped earth and sand.

This invention was made for the purpose of improving the above-mentioned problems.

[Means and Actions for Solving Problems]

In order to achieve the above-mentioned object, the present invention provides the above-mentioned working machine of a swing excavator having a working machine including a boom, an arm, and a bucket in an upper swinging body which is rotatable around the foot, a boom angle detector, and an arm. In the bucket control device of the swing excavator that controls the bucket angle by PID control based on the angle signals detected by the angle detector and the bucket angle detector, the bucket calculated from the boom angle and the arm angle. Differentiate the target angle to obtain the bucket target speed, and add the command value of the obtained bucket target speed to the PID control to control the bucket angle.In addition to the PID control, the bucket speed command By performing the feedforward control, hunting is not likely to occur even if the control gain is increased, so that highly accurate bucket control can be performed.

〔Example〕

 An embodiment of the present invention will be described in detail with reference to the drawings.

In the figure, reference numeral 1 denotes a turning excavator, in which an upper-part turning body 3 is provided on a crawler-type suspension 2 so as to be freely turnable, and a working machine 4 is attached to a front portion of the upper-part turning body.

The working machine 4 is provided with a boom 6 which can be raised and lowered by a boom cylinder 5 and an arm cylinder 7 provided at the tip of the boom 6.
Is attached to the arm 8 which can be freely rotated and the tip of the arm 8. It is composed of a bucket 10 which is rotatable by a bucket cylinder 9.

The working machine 4 includes a boom 6, an arm 8 and a bucket.
Boom angle detector 11 and arm angle detector 12 at each pivot point of 10
And a bucket angle detector 13 are installed respectively, and the angle signals β, detected by these detectors 11 to 13 are
α and γ are input to the control device 14 shown in FIG. 2, respectively.

The control device 14 is provided with an A / D converter 15 for converting the input signals β, α, γ from analog values into digital values, and converts each angle signal β, α, γ into digital values. Then, the boom angle β and the arm angle α are calculated by the target angle calculator 16
The bucket angle γM with respect to the horizontal plane is first calculated by the following equation.

γM = α + β−α ₀ −β ₀ −γ _{0 where} α ₀ is the boom initial value β ₀ is the arm initial value γ ₀ is the bucket initial value The bucket target angle γM calculated by the target angle calculator 16 is sent to the comparator 17. It is compared with the actual bucket angle γ detected by the bucket angle detector 13 and the deviation γM−γ ₀ is input to the PID calculator 18.

The PID calculator 18 calculates how much more the bucket 10 should be rotated from the input deviation, and the PID control signal 1
9 is output to the adder 20.

On the other hand, the bucket target angle γ output from the target angle calculator 16
A part of M is sent to the differentiator 21 and differentiated, and the bucket target speed M is output to the adder 20.

The adder 20 outputs the PID control signal 19 output from the PID calculator 18.
Then, the bucket target speed M output from the differentiator 21 is added and a control signal is output to the electromagnetic proportional control valve 22 provided in the pipeline that supplies the hydraulic pressure to the bucket cylinder 9.

As a result, the bucket 10 is feedforward-controlled by the bucket speed command in addition to the PID control, so that the control characteristic becomes as shown in FIG. Since there is no possibility that hunting will occur even if is raised, the bucket angle can be controlled with high accuracy.

A flow chart of the above operation is shown in FIG.

[Effect of device]

As described in detail above, this device outputs the bucket target speed command value obtained by differentiating the bucket target angle to the control valve for controlling the bucket to perform the angle control of the bucket, in addition to the PID control. Because of the fact that
Compared to what was controlled only by D control, the steady-state error can be reduced, and even if the work implement posture changes, the feedforward control controls the bucket blade edge to follow the target value without stopping, Even if the control gain is increased, there is no risk of hunting as in the conventional case.

As a result, the bucket angle control accuracy can be further improved.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is an overall view of a swing excavator, FIG. 2 is a block diagram of this device, FIG. 3 is a diagram showing control characteristics, and FIG. It is a flowchart. 1 is a turning excavator, 2 is a suspension, 4 is a working machine, 6 is a boom, 8 is an arm, 10 is a bucket, 11 is a boom angle detector,
12 is an arm angle detector and 13 is a bucket angle detector.

Claims (1)

[Scope of utility model registration request] 1. A boom angle detector for a working machine 4 of a revolving excavator 1 having a working machine 4 composed of a boom 6, an arm 8 and a bucket 10 on an upper revolving structure 3 which is rotatable with respect to a suspension 2. 11, an arm angle detector 12 and a bucket angle detector 13 are provided to detect the angle signals β detected by these detectors 11 to 13.
In a bucket control device for a swing excavator that controls a bucket angle γ by PID control based on α and γ, a bucket target speed M is obtained by differentiating the bucket target angle γM calculated from the boom angle β and the arm angle α. A bucket control device for a swivel excavator, wherein the obtained command value of the target bucket speed M is added to the PID control to control the bucket angle.